MSA-20-0003: IP addresses can be spoofed using X-Forwarded-For

X-Forwarded-For headers could be used to spoof a user's IP, in order to bypass remote address checks.

PATCH NOTE: For user IPs to be checked (and logged) accurately after this patch is applied, sites using multiple levels of reverse proxies/balancers that append to the X-Forwarded-For header will need to configure the new "reverseproxyignore" setting. This ensures the IPs of the later proxies are ignored in favour of the user's IP.

Severity/Risk:

Serious

Versions affected:

3.8 to 3.8.1, 3.7 to 3.7.4, 3.6 to 3.6.8, 3.5 to 3.5.10 and earlier unsupported versions